:root {
  --bg: #f4f6fb;
  --bg-doc: #ffffff;
  --surface: #ffffff;
  --surface-2: #eef2fb;
  --border: #d8e0f0;
  --border-strong: #c2cfe6;
  --text: #0f1d3a;
  --text-soft: #50607c;
  --ink: #1d4ed8;
  --ink-strong: #1741b6;
  --ink-soft: #dbe5fb;
  --warn: #b91c1c;
  --warn-bg: #fde8e8;
  --shadow: 0 10px 30px rgba(20, 40, 90, 0.10);
  --radius: 16px;
  --radius-sm: 10px;
  --focus: 0 0 0 3px rgba(29, 78, 216, 0.40);
}

[data-theme="dark"] {
  --bg: #0a1124;
  --bg-doc: #11182e;
  --surface: #131c33;
  --surface-2: #1b2745;
  --border: #283655;
  --border-strong: #36456a;
  --text: #e8eefc;
  --text-soft: #9fb0d0;
  --ink: #5b8cff;
  --ink-strong: #7aa2ff;
  --ink-soft: #1d2d52;
  --warn: #f87171;
  --warn-bg: #3a1b1b;
  --shadow: 0 12px 34px rgba(0, 0, 0, 0.45);
  --focus: 0 0 0 3px rgba(91, 140, 255, 0.45);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  min-height: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  -webkit-text-size-adjust: 100%;
  overflow-x: hidden;
  padding: env(safe-area-inset-top) env(safe-area-inset-right) env(safe-area-inset-bottom) env(safe-area-inset-left);
}

.skip-link {
  position: absolute;
  left: -999px;
  top: 0;
  background: var(--ink);
  color: #fff;
  padding: 10px 14px;
  border-radius: 0 0 10px 0;
  z-index: 100;
}
.skip-link:focus { left: 0; }

/* Header */
.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  padding: 14px clamp(14px, 4vw, 28px);
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}

.brand { display: flex; align-items: center; gap: 12px; min-width: 0; }
.brand-mark {
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--ink), var(--ink-strong));
  color: #fff;
  flex: 0 0 auto;
}
.brand-text { min-width: 0; }
.brand h1 {
  font-size: clamp(1.1rem, 3.4vw, 1.45rem);
  margin: 0;
  line-height: 1.15;
  letter-spacing: -0.01em;
}
.brand-sub {
  margin: 0;
  font-size: 0.82rem;
  color: var(--text-soft);
}

.header-actions { display: flex; align-items: center; gap: 8px; }

/* Buttons */
.btn {
  font: inherit;
  font-weight: 600;
  border: 1px solid var(--border-strong);
  background: var(--surface);
  color: var(--text);
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  transition: transform .12s ease, background .15s ease, border-color .15s ease, box-shadow .15s ease;
  white-space: nowrap;
}
.btn:hover:not(:disabled) { border-color: var(--ink); }
.btn:active:not(:disabled) { transform: translateY(1px); }
.btn:focus-visible { outline: none; box-shadow: var(--focus); }
.btn:disabled { opacity: 0.45; cursor: not-allowed; }

.btn-primary {
  background: linear-gradient(135deg, var(--ink), var(--ink-strong));
  border-color: transparent;
  color: #fff;
}
.btn-primary:hover:not(:disabled) { filter: brightness(1.05); }

.btn-soft { background: var(--surface-2); border-color: var(--border); }
.btn-ghost { background: transparent; border-color: var(--border-strong); }

.btn-warn { color: var(--warn); border-color: var(--warn); background: transparent; }
.btn-warn:hover:not(:disabled) { background: var(--warn-bg); }

.btn-icon {
  width: 44px;
  height: 44px;
  padding: 0;
  position: relative;
  font-size: 1.15rem;
}
.theme-icon { position: absolute; inset: 0; display: grid; place-items: center; transition: opacity .2s ease; }
.theme-icon-dark { opacity: 0; }
[data-theme="dark"] .theme-icon-light { opacity: 0; }
[data-theme="dark"] .theme-icon-dark { opacity: 1; }

.file-btn { position: relative; }

/* Layout */
.layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
  padding: clamp(14px, 3vw, 24px);
  max-width: 1180px;
  margin: 0 auto;
  width: 100%;
}

@media (min-width: 860px) {
  .layout {
    grid-template-columns: minmax(0, 1.6fr) minmax(280px, 0.9fr);
    align-items: start;
  }
}

.panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: clamp(14px, 2.5vw, 20px);
}

/* Canvas stage */
.canvas-stage {
  position: relative;
  width: 100%;
  aspect-ratio: 16 / 9;
  min-height: 160px;
  border: 2px dashed var(--border-strong);
  border-radius: 12px;
  background:
    repeating-linear-gradient(45deg, var(--surface-2) 0 12px, transparent 12px 24px);
  overflow: hidden;
  touch-action: none;
}
.canvas-stage.has-doc {
  border-style: solid;
  background: var(--bg-doc);
}

.layer {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
}
.doc-layer { z-index: 1; background: transparent; }
.sig-layer { z-index: 2; cursor: crosshair; }
.sig-layer:focus-visible { outline: 3px solid var(--ink); outline-offset: -3px; }
.canvas-stage.move-mode .sig-layer { cursor: move; }

.canvas-hint {
  position: absolute;
  inset: 0;
  z-index: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 8px;
  color: var(--text-soft);
  pointer-events: none;
  font-size: 0.95rem;
  opacity: 0.75;
}
.canvas-stage.drawn .canvas-hint { display: none; }

.baseline-note {
  margin: 10px 2px 0;
  font-size: 0.82rem;
  color: var(--text-soft);
}

/* Controls */
.controls-panel { display: flex; flex-direction: column; gap: 18px; }
.control-group { display: flex; flex-direction: column; gap: 10px; }
.group-title {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-soft);
  margin: 0;
  border-bottom: 1px solid var(--border);
  padding-bottom: 6px;
}

.field { display: flex; flex-direction: column; gap: 8px; }
.field > label { font-weight: 600; font-size: 0.92rem; }

.muted { color: var(--text-soft); font-weight: 500; }
.small { font-size: 0.8rem; }

.color-row { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.swatch {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  border: 2px solid var(--border-strong);
  background: var(--sw);
  cursor: pointer;
  padding: 0;
  transition: transform .12s ease, box-shadow .12s ease;
}
.swatch:hover { transform: scale(1.08); }
.swatch[aria-pressed="true"] { box-shadow: 0 0 0 3px var(--ink-soft), 0 0 0 4px var(--ink); }
.swatch:focus-visible { outline: none; box-shadow: var(--focus); }

input[type="color"] {
  width: 40px;
  height: 34px;
  border: 1px solid var(--border-strong);
  border-radius: 8px;
  background: var(--surface);
  cursor: pointer;
  padding: 2px;
}

input[type="range"] {
  width: 100%;
  accent-color: var(--ink);
  height: 28px;
}

.btn-row { display: flex; flex-wrap: wrap; gap: 10px; }
.btn-row .btn { flex: 1 1 auto; min-width: 130px; }

.check-row { display: flex; align-items: center; gap: 10px; font-weight: 600; font-size: 0.92rem; cursor: pointer; }
.check-row input { width: 18px; height: 18px; accent-color: var(--ink); }

/* Toast */
.toast-wrap {
  position: fixed;
  left: 50%;
  bottom: calc(18px + env(safe-area-inset-bottom));
  transform: translateX(-50%);
  z-index: 200;
  display: flex;
  flex-direction: column;
  gap: 8px;
  width: min(92vw, 420px);
  pointer-events: none;
}
.toast {
  background: var(--text);
  color: var(--bg);
  padding: 12px 16px;
  border-radius: 12px;
  box-shadow: var(--shadow);
  font-weight: 600;
  font-size: 0.92rem;
  opacity: 0;
  transform: translateY(12px);
  transition: opacity .25s ease, transform .25s ease;
}
.toast.show { opacity: 1; transform: translateY(0); }
.toast.toast-ok { background: var(--ink); color: #fff; }
.toast.toast-warn { background: var(--warn); color: #fff; }

/* Modal */
.modal-overlay {
  position: fixed;
  inset: 0;
  z-index: 300;
  background: rgba(8, 16, 36, 0.55);
  display: grid;
  place-items: center;
  padding: 20px;
  -webkit-backdrop-filter: blur(2px);
  backdrop-filter: blur(2px);
}
.modal {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 22px;
  width: min(94vw, 420px);
  animation: pop .18s ease;
}
.modal-title { margin: 0 0 8px; font-size: 1.15rem; }
.modal-body { margin: 0 0 18px; color: var(--text-soft); }
.modal-actions { display: flex; justify-content: flex-end; gap: 10px; flex-wrap: wrap; }

.app-footer {
  text-align: center;
  padding: 14px 16px calc(18px + env(safe-area-inset-bottom));
  color: var(--text-soft);
  font-size: 0.82rem;
}

@keyframes pop {
  from { opacity: 0; transform: scale(0.96); }
  to { opacity: 1; transform: scale(1); }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    transition-duration: 0.001ms !important;
  }
}